This project emphasizes 3 approaches related to the structure and function of messenger-RNAs. First the project attempts to define nucleotide sequence and secondary structure features of messenger-RNAs that govern the initiation of protein biosynthesis. Second, the project attempts to develop new methods for the application of ribosome protection procedures to analyze the translation initiation regions of messenger-RNAs. Third, the project attempts to characterize features of RNAs that enhance or restrict 5'-terminal derivatization of messenger-RNAs.